Dreamwidth games! Though pretty much all of them are multi-fandom.

Here's a directory with a lot of current games listed:

https://docs.google.com/spreadsheet/ccc?key=0AmjPoGk4ARJEdE9xcFgwendvLXAzS1lva2hfMTctckE#gid=0

There's also bakerstreet for (often reposted) "memes" (sort of like situation threads) and dear_mun/dear_player, though there's a 4th wall element there since characters have to speak to their muns/players in the initial post.